I must have been 12/13 years old at the time. I had moved up to Secondary School and after sports we all had to strip naked and shower together. This was the first time that many of us had seen other boys totally naked.
My best mate Ken was smaller than me in all ways and I often saw him looking at my cock which was one of the largest in the class and also one of the hairiest. Ken didn't have any pubes at this time and his cock was very small.
We talked sex as all young boys do and I confessed that I was able to masturbate and cum. Ken was fascinated about this and wanted to see it happen, so when we were together at my house I got my cock out and let him see it go hard. He was very impressed. He asked to see me masturbate and though I wanked my cock a little bit for him I felt too embarrassed to cum in front of him.
Next time we were alone in my house he asked me again saying that he didn't believe that I could cum. With a bit of goading I got my cock out again and let him watch me wank off all the way. He was really quite shocked to see cum shooting out of the tip of my cock, and also impressed.
This was the first time I let a guy see me cum - but certainly not the last.
Several months later we were away on a school trip and shared a room. I wanted to wank off as I always did at night and asked if he minded. He jumped at the chance and put the light on to watch me wank. Part way through he asked if he could do it for me. We made a promise that if I let him wank me off he would let me wank him off when he was able to cum.
It felt strange and very nice to have Ken wank me off and I was pleased to shoot a nice amount of cum for him. Sadly he never did repay the compliment.